Tìm x biết: a. x - 3/4 = 3/5 b. x : 1/4 = 16

* Hướng dẫn giải

$\begin{array}{l}a)x-\frac{3}{4}=\frac{3}{5}\\ x=\frac{3}{5}+\frac{3}{4}\\ x=\frac{12}{20}+\frac{15}{20}\\ x=\frac{27}{20}\\ \begin{array}{l}b)x:\frac{1}{4}=16\\ x=16\times \frac{1}{4}\\ x=4\end{array}\end{array}$